1. Field of the Invention
The present invention relates to detachable handles for control devices and particularly to handles for rotary valves which are detachable for safety or to prevent undesired operation.
2. Description of the Prior Art
Detachable handles are fairly common for fluid valves as are valves with stem members designed for operation by wrenches or special tools. The reasons generally relate to security purposes such as where the valve is used to control dangerous fluids or where accidental or careless movement of the valve could upset a critical flow rate. Valves having this feature are usually specially designed for the purpose and have either no handle as such or a special handle that cannot be readily fixed to the valve stem. Many handles can be removed only after removing nuts or bolts. Frequently, and particularly with ball valves, loosening the securing nut loosens the entire stem assembly.
U.S. Pat. No. 3,744,752, assigned to the present assignee, covers a removable handle in which the handle is secured by a spring clip. Since the spring clip is readily removed without tools it does not fill the demand for applications where it is sometimes desired to bolt the handle securely in place.